Incidence and Predictors of Gram-Negative Bacilli in Hospitalized People Who Inject Drugs with Injection Drug Use-Attributable Infections.

The objective of this study was to quantify incidence and determine predictors of Gram-negative bacilli (GNB) in people who inject drugs (PWID) with injection-drug use (IDU)-related infections. The investigation was a retrospective cohort of hospitalized PWID from January 2017 to December 2019. Inclusion criteria were age of ≥18 years, active IDU, treated IDU-attributable infection, and organism growth from microbiology cultures. Infection types included infective endocarditis (IE), acute bacterial skin/skin structure infection (ABSSSI), osteoarticular infection (OAI), and other bloodstream infections (BSI). Primary outcome was GNB identification from microbiologic culture; descriptive statistics were used to describe the cohort. Multivariable regression was used to identify variables associated with GNB infection. A total of 230 PWID were included, 65 (28%) with GNB infections and 165 (72%) with Gram-positive infections. The median (interquartile range [IQR]) population age was 38 (31 to 45) years. Most patients were women (56%); 37% had no insurance. Infection types were as follows: IE, 41%; ABSSSI, 37%; OAI, 20%; and other BSI, 2%. A total of 278 organisms were isolated from 230 patients. The most common organisms were methicillin-resistant Staphylococcus aureus (43%), Streptococcus spp. (19%), methicillin-susceptible S. aureus (17%), and Serratia marcescens (8%); 10% of infections were mixed GNB and Gram-positive infections. A total of 80% of patients received empirical Pseudomonas aeruginosa coverage; only 7% had P. aeruginosa infections. In multivariable regression, age of >50 years (adjusted odds ratio [adjOR], 2.9; 95% confidence interval [CI], 1.2 to 7.2), prior hospitalization within 90 days (adjOR, 2.2; 95% CI, 1.2 to 4.3), and OAI (adjOR, 3.2; 95% CI, 1.5 to 6.6) were associated with GNB infection. GNB in PWID with IDU-attributable infections were more frequently observed in recently hospitalized, older patients with OAI. The majority of patients received empirical antipseudomonal antibiotic coverage, but P. aeruginosa was infrequent. PWID are a potential population to target improved empirical antibiotic use.

Comparison of linezolid step-down therapy to standard parenteral therapy in methicillin-resistant Staphylococcus aureus bloodstream infections.

Data supporting oral step-down therapy in methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI) are sparse; linezolid offers potential in this setting. This study aimed to determine the effectiveness and safety of oral step-down linezolid compared with standard parenteral therapy (SPT) in MRSA-BSI. This was a retrospective cohort performed in adults receiving step-down/outpatient linezolid or SPT (vancomycin, daptomycin) for MRSA-BSI from 2011-2019. Primary outcome was 90-day infection-related re-admission (IRR) from clinical worsening/relapse or infection recurrence. 215 patients included (54 linezolid, 161 SPT). Infection sources were skin (34%), bone/joint (15%), endocarditis (13%), other (32%), multiple (6%). Patients receiving SPT more commonly had complicated bacteraemia (72% vs. 41%; P < 0.0001) and metastatic foci (45% vs. 20%; P = 0.001). 90-day IRR occurred in 17% and 26% of linezolid and SPT groups, respectively (P = 0.159). When accounting for disease severity, linezolid use was not independently associated with 90-day IRR (adjOR, 1.0, 95% CI 0.24-4.3; P = 0.986). There were no differences in all-cause 90-day mortality (4% vs. 6%, P = 0.487) or overall incidence of drug-related adverse events (AEs) (17% vs. 16%; P = 0.843) between the groups. More patients in the SPT group developed an AE requiring re-hospitalisation (12% vs. 2%; P = 0.024), most commonly line-related complications. Oral step-down linezolid demonstrated similar clinical and safety outcomes compared with SPT for MRSA-BSI, except linezolid was associated with fewer AEs requiring re-hospitalisation. Additional research is needed exploring step-down linezolid in MRSA-BSI, particularly in patients requiring shorter durations of outpatient therapy.

Comparison of dalbavancin to standard-of-care for outpatient treatment of invasive Gram-positive infections.

OBJECTIVE: To assess the efficacy and safety of dalbavancin compared to standard-of-care (SOC) or vancomycin and daptomycin in invasive infections due to suspected or confirmed Gram-positive organisms. METHODS: Retrospective cohort of adults who received dalbavancin or SOC on discharge or as an outpatient from 12/2016 to 11/2019. Indications were osteoarticular infection (OAI), infective endocarditis (IE), or other bloodstream infection (BSI). Primary endpoint was 90-day infection-related readmission (IRR); secondary endpoints included time-to-IRR, frequency of adverse drug events (ADEs), and all-cause readmission and mortality. RESULTS: 215 patients were included: 70 (33%) receiving dalbavancin, and 145 (67%) receiving SOC. Indications were OAI (47%), IE (27%), and other BSI (26%). OAI was more common in patients on dalbavancin compared with those receiving SOC (70% vs. 37%, P<0.001). Dalbavancin patients had shorter median (interquartile range [IQR]) length of stay (LOS) prior to drug initiation compared with those receiving SOC (10 [7-17] vs. 13 [9-19], P=0.021). IRR incidence was 17% for dalbavancin patients and 28% for SOC patients. Dalbavancin use was independently associated with lower IRR (adjusted odds ratio [adjOR], 0.10; 95% confidence interval [CI], 0.04-0.31). There was longer median (IQR) time-to-IRR in the dalbavancin group (43 [30-87] vs. 23 [11-63] days, P=0.039), but no differences in all-cause readmission or mortality. Treatment-related ADE incidence was 3% and 14% for the dalbavancin and SOC groups, respectively (P=0.013). Infusion reactions (1/2) and catheter-related complications (1/2) were the most common dalbavancin ADEs; catheter-related complications (14/21), nephrotoxicity (3/21), rhabdomyolysis (2/21), and rash (2/21) were the most common SOC ADEs. CONCLUSIONS: Dalbavancin use was associated with lower 90-day IRR, a shorter hospital LOS prior to therapy, and longer time-to-IRR compared with SOC.